Cargo is frequently transported in containers or pallets, generally referred to as unit load devices, to aid in facilitating loading, unloading and constraining operations. Use of such cargo containers and pallets is particularly desirable when the transport vehicle used is an airplane. When cargo is shipped by aircraft it becomes particularly important that the containers or pallets be securely fastened to the aircraft floor structure to prevent shifting of the cargo during takeoff, landing, and in-flight, where sudden loading conditions may be encountered. In attempting to control and prevent such cargo shifts, and to assist in the loading and unloading of cargo, often quite complex and expensive cargo handling and restraint systems have been devised. One such somewhat complex system is depicted in U.S. Pat. No. 3,899,092 to Nordstrom. The U.S. Pat. No. 3,899,092 patent discloses a modular cargo carrying system which includes beam assemblies, roller trays, and foot operated locks for restraining cargo containers. Such a system is quite complex and expensive, and does not economically and readily lend itself to utilization in a vehicle such as a quick-change passenger/cargo airplane.
In utilizing an airplane for transporting cargo, a large portion of the aircraft floor is typically open to receive cargo. When converting the aircraft from cargo to passenger service, it then becomes necessary to install seats on the floor area which was previously used for cargo. Understandably, it is quite desirable to minimize the time it takes to convert the craft from cargo to passenger, and from passenger to cargo, while simultaneously minimizing the original installation cost and maintenance of any system or devices utilized to speed such conversion.
One approach which has been adopted to enable rapid change from cargo to passenger configurations and vice versa has been to utilize a pallet-supporting structure which will receive either cargo or seat pallets. In such a system, extendable and retractable pallet restraint mechanisms have been provided for securing the pallets to the floor of the aircraft. When it is desired to move cargo or passenger seat pallets over these mechanisms, they are simply retracted below floor level until needed. When needed to perform a restraining function, they can be selectively extended.
In wide body aircrafts, such as the Boeing 747 and the Lockheed L-1011, use of as many as five hundred restraining mechanisms would not be unusual. Thus, a simplicity of construction and cost become quite critical factors. Moreover, simplicity of operation, and the time and effort required to extend and retract such mechanisms, become additional critical factors for changeover in such a large type of vehicle. Finally, because of the critical weight/space considerations attendant to aircraft design, it would be highly desirable to produce a restraint module which, while being strong enough to carry out the intended restraining function, and simple and inexpensive enough to save production and conversion time, is also of a design which will take up a minimum of vertical space in the aircraft cabin. Typically, such retractable and extendable modules take up from 2 to 5 inches, but an efficient, simple and economical module which takes up to about 1 to 11/4 inches would obviously be most desirable.
U.S. Pat. No. 3,906,870 to Alberti shows another retractable cargo restraint mechanism and center-guide means which is quite complex and expensive. Somewhat simpler restraints are depicted in U.S. Pat. Nos. 3,796,397 to Alberti, 3,986,460 to Voigt et al, 3,995,562 to Nordstrom, 4,089,275 to Pelletier, 4,121,789 to Lent, and 4,144,821 to Lang. These patents all show extendable-retractable fore-aft type restraints for cargo handling systems, and share a degree of high cost and complexity of construction and operation, which make them less than ideal for use as a center-guide and side restraint in large quick-change passenger/cargo airplanes.
The container latch of the U.S. Pat. No. 3,796,397 patent to Alberti utilizes a spring loaded pawl to secure a latch-head assembly in an upright extended cargo engaging position. The mechanism requires a somewhat time consuming manual operation and is constructed such that spring failure is critical to the operation of the device. A somewhat sipler-to-activate device is depicted in the U.S. Pat. No. 3,995,562 patent to Nordstrom. The pallet lock in this patent can be retracted and elevated by foot actuation, but requires the operation of springs to carry out the elevation operation, in that the operator's foot merely releases a lock mechanism. Thus, this device is somewhat complex and susceptible to failure in the event of spring failure. In addition, the foot operation to retract requires a double motion, that is, it requires a sideways movement of the foot as well as a downward movement. Moreover, the mechanism is quite complex in involving interaction of locking pawls, springs, etc., and does not readily lend itself to a 1 to 11/4 inch height of construction.
Another pallet lock mechanism which is at least partly operated by foot is depicted in the U.S. Pat. No. 4,089,275 patent to Pelletier. However, the foot operation merely releases a locking mechanism, after which the lock is retracted under the action of a spring force. The lock is elevated by a hand operation. Again, spring action is critical to the operation of the locking mechanism, and the lock is rather complex and expensive in requiring a multiplicity of triggers, springs and the like. Such a system is also not readily adaptable to construction for a 11/4 inch system.
The U.S. Pat. Nos. 4,121,789, 4,144,821 and 3,986,460 patents all offer additional variations on cargo restraint locks, and all are unduly complex in also requiring the use of springs (for successful activation), release mechanisms, and locks, etc. While manual operations are required in the U.S. Pat. Nos. 4,121,789 and 4,144,821 patents, the U.S. Pat. No. 3,986,460 patent can be, to some extent, foot operated. However, the U.S. Pat. No. 3,986,460 construction is quite complex and expensive, requiring many parts, including a constantly projecting roll-over bar which releases a locking member when engaged by a freight container.
In view of the shortcomings of the aforementioned prior art devices, there is a need for an improved cargo restraint module for the restraining of cargo containers and pallets in transport vehicles.
Thus, it is a primary object of this invention to provide a novel cargo unit load device restraint module for use in transport vehicles and, in particular, for an improved restraint mechanism for use in quick-change passenger/cargo airplanes.
It is another object of this invention to provide novel and improved center-guide and side cargo restraint modules and mechanisms that can be entirely and simply foot released, and stick or other such device activated, to provide rapid single step unidirectional motion changeover from a retracted to an extended mode, and vice versa, without complex manual operations and without the need for spring operation.
Still another object of this invention is to provide a novel and improved cargo unit load device restraint module which is of simple and inexpensive design, and which is readily constructable for about 11/4 cargo handling systems.
Yet another object of the invention is to provide a novel and improved cargo unit load device restraint module which, because of its simple construction, is readily adaptable for the inclusion therewith of other cargo or seat pallet handling or guide mechanisms.